The present invention relates generally to an impeller for a pump having at least one blade and designed as a casting, as well as a core arrangement and to a method for casting such an impeller.
Impellers of pumps as a rule are either composed from sheet-metal parts or as castings of plastic or metal. On account of the shape of the flow channels in the impeller, cores are necessary when casting, in order to be able to form undercuts resulting due to the shape of the flow channels. Lost cores are often used with cast impellers of metal.
The cores are often designed in such a complex manner, that the inner contour which defines the negative mold for the impeller to be formed, may often not be completely viewed, to the extent that before casting, one may not recognize as to whether the core is in a perfect condition. Thereby, it is particularly problematic to form the entry region of the flow channels, for example, in particular the blade edge which is at the front in the flow direction, without faults.
It is therefore desirable when manufacturing the core, to be able to ensure that this region is formed in a perfect manner, in order to ensure a faultless shaping of the blade front edge. This is a region which is essential for the flow guidance, and it is particularly with self-priming pumps that this region is formed in a perfect manner, in order to be able to ensure the desired suction power.